Collapsible steering column assembly

ABSTRACT

A collapsible steering column assembly includes: a mounting bracket having a pair of arms and is configured to be fixed to a vehicle body; a supporting housing which is disposed between the pair of arms to be tiltable about the mounting bracket; a steering column which passes through the supporting housing so as to be able to undergo a tilt motion together with the supporting housing; and a locking device which is configured to be in a locking state or an unlocking state to selectively allow a telescopic motion and a tilt motion of the steering column by selectively applying clamping force to the pair of arms. The steering column comprises an outer jacket and an inner jacket which is slidably inserted into the outer jacket. The inner jacket is configured to slide in the supporting housing together with the outer jacket during a telescopic motion of the steering column in the unlocking state of the locking device, and the inner jacket is configured to be able to be collapsed into the outer jacket when impact is applied to the steering column in the locking state of the locking device. The locking device is configured to selectively allow movement of the outer jacket in a direction of the telescopic motion through teeth coupling which is selectively engaged or disengaged depending on the locking state and the unlocking state. It is configured that clearance exists between two teeth of the teeth coupling such that the outer jacket is able to move by a predetermined length in a direction of the telescopic motion in the locking state.

TECHNICAL FIELD

The present invention relates to a collapsible steering column assembly which can be collapsed in the event of collision with an energy absorption function.

BACKGROUND ART

A steering column assembly is an apparatus which is connected to a steering wheel to steer in response to a manipulation of a driver. A steering column assembly is generally configured to allow a tilt motion and a telescopic motion for a convenience of a driver. A tilt motion regulates an angular position of a steering wheel, and the telescopic motion regulates a longitudinal position of a steering column. Also, a locking device is provided which selectively allows the tilt motion and the telescopic motion. The tilt motion and the telescopic motion are restricted so as to maintain a position of the steering wheel when the locking device is in a locking state, and the tilt motion and the telescopic motion are allowed when the locking device is in an unlocking state.

A steering column assembly may be configured to be able to be collapsed while absorbing impact energy at the time of impact such a moment of vehicle collision. That is, when a driver crashes into a steering wheel, an inner jacket of a steering column moves into an outer jacket by impact force so that a steering column is collapsed, and during this process impact energy is absorbed. A steering column having this function is generally called a collapsible steering column.

In order to realize such an energy absorption function, various methods such as a method of interposing a tolerance ring between an inner jacket and an outer jacket, a method of using an energy absorption strap, a method of using deformation of locking teeth or the like have been introduced.

Such a collapsible steering column has corresponding two locking teeth for fixing an outer jacket and rotation of one of the two locking teeth occurs in a conversion between a locking state and an unlocking state, and in such a rotation there is a problem in that collision between the two locking teeth may cause noise and abnormal feeling. Also, since impact is applied in a state that two locking teeth are engaged with one another, there is a problem in that impart energy cannot be effectively absorbed at an early stage of collapse.

PRIOR ART DOCUMENTS

-   -   U.S. Pat. No. 8,375,822 (Date of patent: Feb. 19, 2013)     -   U.S. Pat. No. 8,403,364 (Date of patent: Mar. 26, 2013)     -   U.S. Pat. No. 8,500,168 (Date of patent: Aug. 6, 2013)

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

The present invention has been made in an effort to provide a collapsible steering column assembly in which noise and abnormal manipulation feeling can be removed and stable impact absorption in collapse of a steering column can be secured.

Technical Solution

A collapsible steering column assembly according to an embodiment of the present invention includes: a mounting bracket having a pair of arms and is configured to be fixed to a vehicle body; a supporting housing which is disposed between the pair of arms to be tiltable about the mounting bracket; a steering column which passes through the supporting housing so as to be able to undergo a tilt motion together with the supporting housing; and a locking device which is configured to be in a locking state or an unlocking state to selectively allow a telescopic motion and a tilt motion of the steering column by selectively applying clamping force to the pair of arms. The steering column comprises an outer jacket and an inner jacket which is slidably inserted into the outer jacket. The inner jacket is configured to slide in the supporting housing together with the outer jacket during a telescopic motion of the steering column in the unlocking state of the locking device, and the inner jacket is configured to be able to be collapsed into the outer jacket when impact is applied to the steering column in the locking state of the locking device. The locking device is configured to selectively allow movement of the outer jacket in a direction of the telescopic motion through teeth coupling which is selectively engaged or disengaged depending on the locking state and the unlocking state. It is configured that clearance exists between two teeth of the teeth coupling such that the outer jacket is able to move by a predetermined length in a direction of the telescopic motion in the locking state.

The locking device may include: a lever which is able to rotate between a locking position and an unlocking position; a tilting bolt which is connected to the lever to rotate together with the lever; a cam member which is configured to be able to apply clamping force to the pair of arms in response to rotation of the tilting bolt; a rotating member which is connected to the tilting bolt to rotate together with the tilting bolt; a locking member which is configured to rotate a locking position and an unlocking position by rotation of the rotating member; and a biasing member which provides force to bias the locking member to the locking position.

The cam member may include: a first cam member which is connected to the tilting bolt; and a second cam member which is connected to the first cam member via cam coupling and is supported against an outer surface of the arm of the mounting bracket.

The outer jacket may have a first locking teeth consisting of the teeth coupling. The rotating member may include: a body portion which is connected to the tilting bolt; a pair of legs which are protruded from both ends of the body portion; and a driving rod which connects the pair of legs. The locking member may include: a slot into which the driving rod is inserted; and a second locking teeth which is configured to be able to be selectively engaged with the first locking teeth.

The first locking teeth and the second locking teeth are configured to have clearance therebetween so as not to collide with one another when the rotating member rotates about a longitudinal axis of the tilt blot in a state before the steering column is collapsed.

The steering column further may include a tolerance ring which is interposed between the outer jacket and the inner jacket, and wherein a telescopic motion that the inner jacket and the outer jacket slide together and collapse of the inner jacket into the outer jacket are realized through the tolerance ring.

A collapsible steering column assembly according to another embodiment of the present invention includes: a mounting bracket having a pair of arms and is configured to be able to be fixed to a vehicle body; a supporting housing which is disposed between the pair of arms to be tiltable about the mounting bracket; a steering column which passes through the supporting housing so as to be able to undergo a tilt motion together with the supporting housing; and a locking device which is configured to be a locking state or an unlocking state to selectively allow a telescopic motion and a tilt motion of the steering column by selectively applying clamping force to the pair of arms. The steering column includes an outer jacket and an inner jacket which is partially inserted into the outer jacket so as to be able to slide in a direction of a telescopic motion together with the outer jacket in the unlocking state of the locking device and so as to be able to be collapsed into the outer jacket when impact is applied in the locking state of the locking device, and the locking device is configured such that movement of the outer jacket is blocked after moving by a predetermined length in a direction of the telescopic motion when impact is applied in the locking state.

The locking device may be configured to selectively block movement of the outer jacket in the locking state via teeth coupling between a pair of locking teeth which are selectively engaged or disengaged depending on the locking state and the unlocking state, and movement of the outer jacket in a direction of the telescopic motion in the locking state may be realized by a clearance between the pair of locking teeth.

The locking device may include: a lever which is able to rotate between a locking position and an unlocking position; a tilting bolt which is connected to the lever to rotate together with the lever; a cam member which is configured to be able to apply clamping force to the pair of arms in response to rotation of the tilting bolt; a rotating member which is connected to the tilting bolt to rotate together with the tilting bolt; a locking member which is configured to rotate a locking position and an unlocking position by rotation of the rotating member; and a biasing member which provides force to bias the locking member to the locking position.

The outer jacket may have a first locking teeth consisting of the teeth coupling. The rotating member may include: a body portion which is connected to the tilting bolt; a pair of legs which are protruded from both ends of the body portion; and a driving rod which connects the pair of legs. The locking member may include: a slot into which the driving rod is inserted; and a second locking teeth which is configured to be able to be selectively engaged with the first locking teeth.

The first locking teeth and the second locking teeth may be configured to have clearance therebetween so as not to collide with one another when the rotating member rotates about a longitudinal axis of the tilt blot in a state before the steering column is collapsed.

The steering column may further include a tolerance ring which is interposed between the outer jacket and the inner jacket, and collapse of the inner jacket into the outer jacket may be realized through the tolerance ring.

A collapsible steering column assembly according to another embodiment of the present invention includes: a mounting bracket having a pair of arms and is configured to be able to be fixed to a vehicle body; a supporting housing which is disposed between the pair of arms to be tiltable about the mounting bracket; a steering column which passes through the supporting housing so as to be able to undergo a tilt motion together with the supporting housing; and a locking device which is configured to be a locking state or an unlocking state to selectively allow a telescopic motion and a tilt motion of the steering column by selectively applying clamping force to the pair of arms. The steering column comprises an outer jacket and an inner jacket which is partially inserted into the outer jacket so as to be able to slide in a direction of a telescopic motion together with the outer jacket in the unlocking state of the locking device and so as to be able to be collapsed into the outer jacket when impact is applied in the locking state of the locking device, and the locking device is configured to selectively block movement of the outer jacket in a direction of the telescopic motion in collapse of the inner jacket by impact in the locking state through selective engagement of a pair of locking teeth. The pair of locking teeth comprises a first locking teeth provided to the outer jacket and a second locking teeth which is rotatable to be able to be selectively engaged with the first locking teeth depending on the locking state and the unlocking state of the locking device. A a clearance which makes the second locking teeth not collide with the first locking teeth while the second locking teeth rotates for a conversion from the locking state to the unlocking state exists between the first locking teeth and the second locking teeth.

The locking device may include: a lever which is able to rotate between a locking position and an unlocking position; a tilting bolt which is connected to the lever to rotate together with the lever; a cam member which is configured to be able to apply clamping force to the pair of arms in response to rotation of the tilting bolt; a rotating member which is connected to the tilting bolt to rotate together with the tilting bolt; a locking member which is configured to rotate a locking position and an unlocking position by rotation of the rotating member; and a biasing member which provides force to bias the locking member to the locking position.

The rotating member may include: a body portion which is connected to the tilting bolt; a pair of legs which are protruded from both ends of the body portion; and a driving rod which connects the pair of legs. The locking member may have a slot into which the driving rod is inserted, and the first locking teeth may be provided to the outer jacket and the second locking teeth is provided to the locking member.

The steering column may further include a tolerance ring which is interposed between the outer jacket and the inner jacket, and a telescopic motion that the inner jacket and the outer jacket slide together and collapse of the inner jacket into the outer jacket may be realized through the tolerance ring.

Advantageous Effects

According to the present invention, since there is a clearance between locking teeth of a locking device, noise and abnormal manipulation feeling generated by a collision of locking teeth can be prevented and stable impact absorption in collapse of a steering column can be secured.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a collapsible steering column assembly according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along a line II-II in FIG. 1.

FIG. 3 is an enlarged view of a portion in FIG. 2.

FIG. 4 illustrates a locking state of a telescopic motion in a collapsible steering column assembly according to an embodiment of the present invention.

FIG. 5 illustrates an unlocking state of a telescopic motion in a collapsible steering column assembly according to an embodiment of the present invention.

FIG. 6 illustrates locking teeth of a locking device of a collapsible steering column assembly according to an embodiment of the present invention.

FIG. 7 illustrates a state in which an outer jacket has been moved by impact from the state shown in FIG. 6.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1 and FIG. 2, a collapsible steering column assembly includes a steering column 10. The steering column 10 may include an inner jacket 11 and an outer jacket 12. One end portion of the inner jacket 11 is inserted into the outer jacket 12 to be movable in a longitudinal direction. At this time, a steering wheel (not shown) may be coupled to an end of a steering column, and steering shafts 13 and 14 which are connected to one another to be relatively movable relative to one another may be connected to the inner jacket 11 and the outer jacket 12. When impact force which may cause collapse of a steering column is applied to the steering wheel, the inner jacket 11 may be pushed to move into the outer jacket 12 with the steering shaft 13 so that collapse of the steering column occurs, and during this process energy absorption occurs. This will be again described later.

At this time, as exemplarily shown in FIG. 1, the steering column 10 may be configured to be able to move in a telescopic direction 15 and to be able to tilt in a tilt direction 16.

Meanwhile, as shown in FIG. 1 and FIG. 2, the collapsible steering column assembly includes a mounting bracket 20. The mounting bracket 20 may be configured to be fixed to a vehicle body and may have a pair of arms 21 which face one another. The arms 21 are formed to be elastically deformed in a direction toward one another when external force (clamping force) is applied thereto.

Referring to FIG. 1 and FIG. 2, the collapsible steering column assembly includes a supporting housing 22 which is tiltably connected to the mounting bracket 20. For example, the supporting housing 22 may be connected to the mounting bracket 20 via a tilt shaft 24 to be tiltable. At this time, a tilt direction of the supporting housing 22 may be the same with the tilt direction 16 of the steering column 10. The supporting housing 22 may be a receiving space of a cylindrical shape which is elongated in a longitudinal direction, the steering column 10 may be slidably disposed in the receiving space. A telescopic motion of the steering column 10 may occur by sliding of the steering column 10 within the supporting housing 22, and a tilt motion of the steering column 10 may occur by tilting of the steering column 10 with the supporting housing 22. That is, the steering column 10 may be inserted into the supporting housing 22 to be able to undergo a telescopic motion via a relative movement to the supporting housing 22 and a tilt motion via a tilting movement together with the supporting housing 22.

The supporting housing 22 may include a pair of legs 23 which are formed to be able to face the pair of arms 21 of the mounting bracket 20. As shown in FIG. 1, the pair of legs 23 of the supporting housing 22 may be spaced from one another while respectively contacting inner surfaces of the pair of arms 21 of the mounting bracket 20.

A biasing member 25 for preventing the supporting housing 22 and the steering column 10 which is supported thereto from falling down may be provided. The biasing member 25 may be a coil spring having an elastic resilient force, and one end thereof may be connected to the mounting bracket 20 and the other end thereof may be connected to the supporting housing 22.

As shown in FIG. 1 and FIG. 2, the inner jacket 11 and the outer jacket 12 may pass between the pair of arms 21 of the mounting bracket 20 while passing through the supporting housing 22.

Referring to FIG. 1 to FIG. 3, the collapsible steering column assembly includes a locking device 30 which operates to selectively block or allow a telescopic motion and a tilt motion. The locking device 30 may selectively be in a locking position or an unlocking position, and a telescopic motion and a tilt motion are blocked in the locking position and are allowed in the unlocking position. The locking device 30 is configured to selectively apply clamping force to the pair of arms 21 of the mounting bracket 20 so as to operate to selectively allow the telescopic motion and the tilt motion.

The locking device 30 may include a lever 31 which can rotate between a locking position and an unlocking position and a tilting bolt 32 which is connected to the lever 31 so as to rotate together with the lever 31. The lever 31 may be formed to be rotated by a driver's hand, and the tilting bolt 32 may pass through the pair of arms 21 of the mounting bracket 20 and the pair of legs 23 of the supporting housing 22. The tilting bolt 32 defines a longitudinal axis passing across the pair of arms 21 of the mounting bracket 20 and the pair of legs 23 of the supporting housing 22, and is configured to be able to rotate about this longitudinal axis. At this time, both end portions of the tilting bolt 32 are jutted out from outer side of the first and the second arms 21 of the mounting bracket 20, and the lever 31 may be connected to one end portion and a fixing nut 33 may be connected to the other end portion. Under these configurations, the tilting bolt 32 can rotate about its longitudinal axis by the rotation of the lever 31.

The locking device 30 may include cam members 34 and 35 which are respectively disposed between the arm 21 of the mounting bracket 20 and the lever 31 and between the mounting bracket 20 and the fixing nut 33. The outer cam member 34 may be connected to the tilting bolt 32 to rotate together with the tilting bolt 32, and the inner cam member 35 may be connected to the tilting bolt 32 to be able to move in a longitudinal axis thereof. The outer cam member 34 and the inner cam member 35 have cam surfaces respectively, and if the tilting bolt 32 rotates to the locking position, the inner cam member 35 is pushed by the outer cam member 34 to move toward the arm 21 of the mounting bracket 20. That is, when the locking device 30 is in the locking state, the arm 21 of the mounting bracket 20 and the leg 23 of the supporting housing 22 are pressurized by clamping force of the cam member 35 to be contracted inwardly, and accordingly the outer jacket 12 and the inner jacket 11 are sequentially pressurized so that the telescopic motion and the tilt motion can be blocked. That is, the arms 21 of the mounting bracket 20 is inwardly contracted by the clamping force in the locking state so as to pressurize the legs 23 and accordingly the legs 23 of the supporting housing 22 are also inwardly contracted to tightly contact an outer surface of the outer jacket 12. Thereby, a telescopic movement of the outer jacket 12 within the supporting housing 22 so that a telescopic motion of the steering column 10 is blocked, and a tilt of the supporting housing 22 is also blocked so that a tilt motion of the steering column 10 is also blocked.

A return spring 36 for assisting returning of the pair of legs 23 of the supporting housing 22 to their original position during the conversion from the locking state to the unlocking state may be provided. The return spring 36 may be set to elastically outwardly support the pair of legs 23.

The locking device 30 may further include a structure for selectively blocking movement of the outer jacket 12 in a telescopic direction. For this, the locking device 30 may include a rotating member 37 which is connected to the tilting bolt 32 so as to rotate with the tilting bolt 32 about a longitudinal axis of the tilting bolt 32. As shown in FIG. 1, the rotating member 37 may be disposed between the pair of arms 21 of the mounting bracket 20. The rotating member 37 may include a body portion 38 which is elongated along a longitudinal axis of the tilting bolt 32 and through which the tilting bolt 32 passes, a first and a second legs 39 which are protruded from both ends of the body portion 38 and a driving rod 40 which connects the two legs 39.

Also, the locking device 30 may include a locking member 41 for a locking function. The locking member 41 is configured to be operated by the rotating member 37 and is disposed between the pair of arms 21 of the mounting bracket 20 in the vicinity of the rotating member 37. The locking member 41 is rotatably connected to a connecting rod 42 which is connected respectively to the pair of legs 23 of the supporting housing 22. Referring to FIG. 5, the locking member 41 may have a slot 43 into which the driving rod 40 of the rotating member 37 is inserted, and the slot 43 may be formed to be larger than the driving rod 40. If the rotating member 37 rotates in a clock wise in FIG. 3 about the tilting bolt 32 by the rotation of the lever 31, the locking member 41 rotates in a counter-clock wise in FIG. 3 about the connecting rod 42 by the driving rod 40.

Locking teeth (first locking teeth) 45 are formed on an outer surface of the outer jacket 12, and correspondingly the locking member 41 has locking teeth (second locking teeth) 44. If the locking teeth 44 of the locking member 41 and the locking teeth 45 of the outer jacket 12 are engaged with one another, movement of the outer jacket 12 along a longitudinal direction is blocked, and if two teeth 44 and 45 are disengaged, the blocking of the movement of the outer jacket 12 in a longitudinal direction is removed.

The locking device 30 may include a biasing member 46 which provides a biasing force to urge the locking member 41 to be in the locking state. For example, the biasing member 46 may be formed of material having an elastic resilient force, and the biasing member 46 provides a biasing force by elastically supporting the locking member 41 to be in the locking position by an elastic resilient force as shown in FIG. 1 to FIG. 3.

A tolerance ring 50 may be interposed between the inner jacket 11 and the outer jacket 12. The tolerance ring 50 is disposed to contact the outer circumferential surface of the inner jacket 11 and an inner circumferential surface of the outer jacket 12 to generate friction force therebetween which urges the inner jacket 11 and the outer jacket 12 to move together during a telescopic motion. Meanwhile, during the collapse of the steering column, the tolerance ring 50 performs an energy absorption function while allowing the inner jacket 11 to move into the outer jacket 12. For example, when external impact is applied to the steering column, energy absorption occurs while the tolerance ring 50 deforms or an outer surface of the inner jacket 11 and/or an inner surface of the outer jacket 12 is damaged, and during this process the inner jacket 11 is further inserted into the outer jacket 12 so that the steering column is collapsed.

Referring to FIG. 4 and FIG. 5, locking function by teeth engagement of the locking device 30 will be described in more detail. FIG. 4 shows the locking state by teeth engagement, and FIG. 5 shows the unlocking state by teeth disengagement. Referring to FIG. 4, when the lever 31 is in the locking position, the rotating member 37 and the locking member 41 are in the locking position shown in FIG. 4 and thereby the locking teeth 44 of the locking member 41 and the locking teeth 45 of the lower jacket 12 are engaged with one another so that a movement of the outer jacket 12 is blocked. That is, in the locking state of the locking device 30, since the locking teeth 45 and the locking teeth 44 are engaged with one another, a movement of the outer jacket 12 in a telescopic direction is additionally blocked in addition to the locking of the telescopic motion by the clamping force of the locking device in the locking state. Meanwhile, referring to FIG. 5, when the lever 31 is rotated to the unlocking position, the rotating member 37 rotates about the tilting bolt 32 to raise the locking member 41 and thus the locking teeth 44 of the locking member 41 is disengaged from the locking teeth 44 of the outer jacket 12 so that a telescopic movement of the outer jacket 12 is allowed.

According to an embodiment of the present invention, it is configured that a clearance exists between the first and the second locking teeth 45 and 44 of the locking device 30. For example, as shown in FIG. 6, a clearance d1 in a collapsing direction and a clearance d2 in a direction approximately perpendicular to this may exist between the first and the second locking teeth 45 and 44. Due to such clearance, when the locking device 30 is in the locking state, i.e., the state shown in FIG. 6, the first and the second locking teeth 45 and 44 contact each other as shown in FIG. 7 after the outer jacket 12 moves by a predetermined distance (distance determined depending on the clearance). That is, if impact which can overcome the clamping force of the locking device 30 in the locking state shown in FIG. 6 is applied to the steering column, the outer jacket 12 moves in a direction of an arrow in FIG. 7 while only overcoming the clamping force until the clearance between the first and the second locking teeth 45 and 44 is disappeared. Then, from the state shown in FIG. 7, a further movement of the outer jacket 12 is blocked by the contact of the first and the second locking teeth 45 and 44, and in this state the inner jacket 11 is collapsed into the outer jacket 12. According to an embodiment of the present invention, when impact is applied in the locking state of the locking device 30, impact force is not applied to a portion where the clamping force of the locking device and to the teeth engagement of the locking teeth at the same time, but a portion where the clamping force is acted absorbs the impact until the clearance between the locking teeth 45 and 44 is disappeared, and then the impact force is acted to the locking teeth 45 and 44 only after the clearance disappears. Due to this configuration, more stable impact absorption can be obtained during the collapse of the steering column by impart in the locking state of the locking device.

The clearance between the first and the second locking teeth 45 and 44 may prevent noise or abnormal manipulation feeling which may be caused by collision between the locking teeth which may occur during the conversion from the locking state to the unlocking state. That is, the two locking teeth may collide with one another so as to generate noise or abnormal manipulation feeling if there is no clearance between the two locking teeth, but in an embodiment of the present invention due to the clearance between the locking teeth, a collision of the second locking teeth 44 to the first locking teeth 45 can be prevented when the second locking teeth 44 rotates for the conversion from the locking state to the unlocking state. For this, referring to FIG. 6, it is configured such that rotation locus of respective ends of the second locking teeth 44 are positioned at the outside of the first locking teeth 45 when the locking member 41 rotates about its rotation center axis RX for conversion to the unlocking state.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

INDUSTRIAL APPLICABILITY

The present invention relates to a steering column assembly of a vehicle, so it has an industrial applicability. 

The invention claimed is:
 1. A collapsible steering column assembly comprising: a mounting bracket having a pair of arms and is configured to be fixed to a vehicle body; a supporting housing which is disposed between the pair of arms to be tiltable about the mounting bracket; a steering column which passes through the supporting housing so as to be able to undergo a tilt motion together with the supporting housing; and a locking device which is configured to be in a locking state or an unlocking state to selectively allow a telescopic motion and a tilt motion of the steering column by selectively applying clamping force to the pair of arms, wherein the steering column comprises an outer jacket and an inner jacket which is slidably inserted into the outer jacket, wherein the inner jacket is configured to slide in the supporting housing together with the outer jacket during a telescopic motion of the steering column in the unlocking state of the locking device, wherein the inner jacket is configured to be able to be collapsed into the outer jacket when impact is applied to the steering column in the locking state of the locking device, wherein the locking device is configured to selectively allow movement of the outer jacket in a direction of the telescopic motion through teeth coupling which is selectively engaged or disengaged depending on the locking state and the unlocking state, and wherein it is configured that clearance exists between two teeth of the teeth coupling such that the outer jacket is able to move by a predetermined length in a direction of the telescopic motion in the locking state.
 2. The collapsible steering column assembly of claim 1, wherein the locking device comprises: a lever which is able to rotate between a locking position and an unlocking position; a tilting bolt which is connected to the lever to rotate together with the lever; a cam member which is configured to be able to apply clamping force to the pair of arms in response to rotation of the tilting bolt; a rotating member which is connected to the tilting bolt to rotate together with the tilting bolt; a locking member which is configured to rotate a locking position and an unlocking position by rotation of the rotating member; and a biasing member which provides force to bias the locking member to the locking position.
 3. The collapsible steering column assembly of claim 2, wherein the cam member comprises: a first cam member which is connected to the tilting bolt; and a second cam member which is connected to the first cam member via cam coupling and is supported against an outer surface of the arm of the mounting bracket.
 4. The collapsible steering column assembly of claim 2, wherein the outer jacket has a first locking teeth consisting of the teeth coupling, and wherein the rotating member comprises: a body portion which is connected to the tilting bolt; a pair of legs which are protruded from both ends of the body portion; and a driving rod which connects the pair of legs, and wherein the locking member comprises: a slot into which the driving rod is inserted; and a second locking teeth which is configured to be able to be selectively engaged with the first locking teeth.
 5. The collapsible steering column assembly of claim 4, wherein the first locking teeth and the second locking teeth are configured to have clearance therebetween so as not to collide with one another when the rotating member rotates about a longitudinal axis of the tilting blot in a state before the steering column is collapsed.
 6. The collapsible steering column assembly of claim 1, wherein the steering column further comprises a tolerance ring which is interposed between the outer jacket and the inner jacket, and wherein a telescopic motion that the inner jacket and the outer jacket slide together and collapse of the inner jacket into the outer jacket are realized through the tolerance ring.
 7. A collapsible steering column assembly comprising: a mounting bracket having a pair of arms and is configured to be able to be fixed to a vehicle body; a supporting housing which is disposed between the pair of arms to be tiltable about the mounting bracket; a steering column which passes through the supporting housing so as to be able to undergo a tilt motion together with the supporting housing; and a locking device which is configured to be a locking state or an unlocking state to selectively allow a telescopic motion and a tilt motion of the steering column by selectively applying clamping force to the pair of arms, wherein the steering column comprises an outer jacket and an inner jacket which is partially inserted into the outer jacket so as to be able to slide in a direction of a telescopic motion together with the outer jacket in the unlocking state of the locking device and so as to be able to be collapsed into the outer jacket when impact is applied in the locking state of the locking device, and wherein the locking device is configured such that movement of the outer jacket is blocked after moving by a predetermined length in a direction of the telescopic motion when impact is applied in the locking state.
 8. The collapsible steering column assembly of claim 7, wherein the locking device is configured to selectively block movement of the outer jacket in the locking state via teeth coupling between a pair of locking teeth which are selectively engaged or disengaged depending on the locking state and the unlocking state, and wherein movement of the outer jacket in a direction of the telescopic motion in the locking state is realized by a clearance between the pair of locking teeth.
 9. The collapsible steering column assembly of claim 8, wherein the locking device comprises: a lever which is able to rotate between a locking position and an unlocking position; a tilting bolt which is connected to the lever to rotate together with the lever; a cam member which is configured to be able to apply clamping force to the pair of arms in response to rotation of the tilting bolt; a rotating member which is connected to the tilting bolt to rotate together with the tilting bolt; a locking member which is configured to rotate a locking position and an unlocking position by rotation of the rotating member; and a biasing member which provides force to bias the locking member to the locking position.
 10. The collapsible steering column assembly of claim 9, wherein the outer jacket has a first locking teeth consisting of the teeth coupling, and wherein the rotating member comprises: a body portion which is connected to the tilting bolt; a pair of legs which are protruded from both ends of the body portion; and a driving rod which connects the pair of legs, and wherein the locking member comprises: a slot into which the driving rod is inserted; and a second locking teeth which is configured to be able to be selectively engaged with the first locking teeth.
 11. The collapsible steering column assembly of claim 10, wherein the first locking teeth and the second locking teeth are configured to have clearance therebetween so as not to collide with one another when the rotating member rotates about a longitudinal axis of the tilting blot in a state before the steering column is collapsed.
 12. The collapsible steering column assembly of claim 7, wherein the steering column further comprises a tolerance ring which is interposed between the outer jacket and the inner jacket, and wherein collapse of the inner jacket into the outer jacket is realized through the tolerance ring.
 13. A collapsible steering column assembly comprising: a mounting bracket having a pair of arms and is configured to be able to be fixed to a vehicle body; a supporting housing which is disposed between the pair of arms to be tiltable about the mounting bracket; a steering column which passes through the supporting housing so as to be able to undergo a tilt motion together with the supporting housing; and a locking device which is configured to be a locking state or an unlocking state to selectively allow a telescopic motion and a tilt motion of the steering column by selectively applying clamping force to the pair of arms, wherein the steering column comprises an outer jacket and an inner jacket which is partially inserted into the outer jacket so as to be able to slide in a direction of a telescopic motion together with the outer jacket in the unlocking state of the locking device and so as to be able to be collapsed into the outer jacket when impact is applied in the locking state of the locking device, wherein the locking device is configured to selectively block movement of the outer jacket in a direction of the telescopic motion in collapse of the inner jacket by impact in the locking state through selective engagement of a pair of locking teeth, wherein the pair of locking teeth comprises a first locking teeth provided to the outer jacket and a second locking teeth which is rotatable to be able to be selectively engaged with the first locking teeth depending on the locking state and the unlocking state of the locking device, and wherein a clearance which makes the second locking teeth not collide with the first locking teeth while the second locking teeth rotates for a conversion from the locking state to the unlocking state exists between the first locking teeth and the second locking teeth.
 14. The collapsible steering column assembly of claim 13, wherein the locking device comprises: a lever which is able to rotate between a locking position and an unlocking position; a tilting bolt which is connected to the lever to rotate together with the lever; a cam member which is configured to be able to apply clamping force to the pair of arms in response to rotation of the tilting bolt; a rotating member which is connected to the tilting bolt to rotate together with the tilting bolt; a locking member which is configured to rotate a locking position and an unlocking position by rotation of the rotating member; and a biasing member which provides force to bias the locking member to the locking position.
 15. The collapsible steering column assembly of claim 14, wherein the rotating member comprises: a body portion which is connected to the tilting bolt; a pair of legs which are protruded from both ends of the body portion; and a driving rod which connects the pair of legs, wherein the locking member comprises a slot into which the driving rod is inserted, and wherein the first locking teeth is provided to the outer jacket and the second locking teeth is provided to the locking member.
 16. The collapsible steering column assembly of claim 13, wherein the steering column further comprises a tolerance ring which is interposed between the outer jacket and the inner jacket, and wherein a telescopic motion that the inner jacket and the outer jacket slide together and collapse of the inner jacket into the outer jacket are realized through the tolerance ring. 